Complexed plating electrolyte and method of plating therewith



Stts

COMPLEXED PLATING ELECTROLYTE AND METHOD OF PLATING THEREWITH I Kurt E. Schimkus, Chicago, 11]., assignor to Acme Steel Company, Chicago, 11L, a corporation of Illinois This invention relates to improvementsin methods of electroplating base metals and to improved plating baths therefor and to improved coatings made thereby.

The present invention contemplates the electroplating of copper, zinc, tin, nickel, cobalt, cadmium, tungsten, manganese and lead, and alloys thereof including brass and bronze on base metals. Heretofore the plating of copper and alloys thereof on steel has been effected chiefly by two methods, one of which is known as the cyanide or alkaline method, while the other is known as the acid sulfate method. Other methods include the pyrophosphate method and the fluoborate method, each of these being less important from a commercial standpoint today. In the cyanide method the electrolyte consists of a solution including sodium cyanide (NaCN) and copper cyanide (CuCN) in water. The use of this electrolyte has the major disadvantage that the cyanide ingredient is a deadly poison so that special provisions must be made for the control of fumes and for the disposal of waste, thus requiring greater expense due to the greater amount of equipment required for this purpose. In addition, the use of a cyanide bath generally requires the use of a so-called strike to start the plating operation, for example, a quick initial electrodeposition of copper by means of a cyanide bath. The need for the strike arises when plating copper directly upon iron. The spongy copper deposited on the surface of iron by immersion plating prevents subsequent deposition of an adherent coat since the spongy copper does not readily adhere to the iron. By means of a strike of copper, an adherent thin layer of copper is applied, over which adherent copper deposition may be further continued. So far, a satisfactory strike has only been achieved commercially by the use of a cyanide bath. Another disadvantage of a cyanide bath is that it must be maintained at a temperature of from 120 degrees to 140 degrees F. This requires the addition of heating equipment to maintain the bath temperature in this range which is considerably above the ordinary room temperature.

The acid sulfate method uses a solution consisting essentially of a solution of copper sulfate (CuSO and sulfuric acid (H 50 The acid sulfate method is a very eflicient one. Its major disadvantage is that it also requires the use of a cyanide strike in order to obtain an adherent copper coating on iron. In some cases, where there is no flexing of the plated metal or where copper foil is being manufactured by means of electrodeposition and it is subsequently required to be peeled from the iron on which it is coated, an adherent coating is not required and, in these cases, the strike is eliminated. However, for an adherent copper coating, as already mentioned, the strike is required.

The pyrophosphate electrolyte comprises a solution of sodium pyrophosphate (Na P 0 or potassium pyro- 2,973,398 Patented Feh. 28, 1961 and the more expensive equipment is still required even though the pyrophosphates themselves are not harmful. Further, as in the case of the cyanide method, the pyro-' phosphate bath must also be maintained at an elevated temperature approximating that of the cyanide bath, thus still requiring the use of expensive heating equipment. The reason that the pyrophosphate method has achieved any distinction in commerce today is because some companies have suggested that a pyrophosphate strike may be used in place of the cyanide strike. However, this has not proved to be satisfactory, with the result that the cyanide strike is the only one now substantially em* ployed in commercial practice.

The fluoborate bath issimilar in operation to the acid sulfate bath. It contains Cu(BF KBF, and H BO This method is the least important since its use is quite insignificant. Further, it also requires the use of a strike in order to obtain an adherent copper coating.

In order to obtain an adherent coating, the cyanide strike has been required in any case, and it has been necessary to install the expensive cyanide equipment. Therefore, it is quite customary for one who has installed equipment for the cyanide strike to proceed with the cyanide bath for completion of the copper plating without turning to the use of pyrophosphates or any other types of plating baths.

Similar problems are also encountered when attempting to electroplate coatings of the other metals listed above on base metals.

Accordingly, it is an important object of the present invention to provide an improved method of plating metals on base metals, and improved plating baths therefor and an improved coating made thereby.

Another ob ect of the invention is to provide an improved method of electroplating which utilizes nontoxic materials which can be readily disposed of without special precautions regarding the toxicity thereof.

'Yet another object of the invention is to provide an improved plating method of the type set forth which produces adherent uniform coats of metals on base metals, the metal coatings having good appearance.

Still another ob ect of tne invention is to provide an improved electroplating method, bath and coating made thereby which carries in addition an adherent organic protective coating thereon.

It has now been found that the above objects and advantages of the invention are realized by electroplating from a bath containing the cation of the metal to form the coating and an anion of a phosphoric acid ester of cyclohexanol dissolved in water. A preferred class of ion materials is the anion of a phosphoric ester of hexahydroxycylohexane (inositol), the preferred anion material being the anion of inositol hexaphosphoric acid commonly called phytic acid. It also has been found that the anion materials may be applied as a free acid or as a salt thereof, the sodium, potassium, calcium and magnesium salts being particularly advantageous.

The electroplating method can be successfully operated in the pH range of about 0.5 to about 13, the material being plated out to form the coating and the phytic acid or other related material of necessity being soluble at the pH chosen for operation. The concentration of the phytic acid or other related anion material used in the present invention is preferably sufiicient to form a complex with substantially all of the metallic cations in solution, although good success has been achieved when less than the amount required to complex all of the cations present has been used. By properly selecting the operating pH and the concentration of the complexing ion, good coatings can be obtained at reasonable operating potentials and current densities within a reasonable length of time.

IS "3 The following specific examples of electroplating meth= ods and plating baths and the coatings made thereby illustrate the application of the present invention but it is to be understood that these examples are not intended in any way to limit the scope oflthe pre'sent invention.

EXAMPLE 1 An electrolytic bath was made up by mixing the following ingredients in the amounts indicated in one gallon of water.

' Ounces SOdium phytate (C H O 4P5)Naj2 1 Copper tartrate 10 The electrolyte solution was placed in. a tank having an anode of pure copper and the base metal to'be' plated serving as the cathode. The solution was moderately agitated during the plating operation. The pH was maintained at 9.51:0.5 and the temperature was maintained in the range of about 75 F. to 80 F. The plating current density was about 30 amperes per square foot at a potential of 33 volts. Steel straps 2 inches wide, 6 inches long and 0.02 inch thick were plated. The copper coating formed thereon was hard, smooth and uniform in finish and firmly adhered to the underlying base metal.

When the electrolyte is prepared, it is believed that a copper complex is formed with the phytate anion and that the copper cations pass from the complex to the base metal being plated during the plating operation, the-copper anode replacing the copper cations in solution and in the complex. In addition, there are present in the bath small amounts of copper ions which are not complexed but preferably the amount of copper ions not complexed is reduced to a minimum since such copper ions may form a displacement coating which readily rubs off and is not adherent. It is desirable therefore when plating with cop-. per alone to have sufiicient sodium phytate present in the solution of Example 1 to insure that substantially all of the copper in thebath is complexed thereby. If insufficient sodium phytate is present, the copper will be de-.

posited on the base metal as an immersion displacement coating which readily rubs oif or the copper will be precipitated from the solution as copper hydroxide or the like.

Other sources of copper ion can be used in place of the copper tartrate illustrated in Example 1. For example, copper sulfate, copper carbonate or other soluble copper salts may be used. The concentration of the sodium phytate may vary from about 8 ounces per gallon of solution to about 14 ounces per gallon of solution.

It has been found that the presence of a small amount of zinc in the electrolyte improves the quality of the coatingwithout substantially changing the color thereof. The following is an example of such an electrolyte and the manner of using it to achieve an improved copper coating on steel.

EXAMPLE 2 A solution was prepared by adding the following ingradients to water in the amounts indicated.

I Copper tartrate, grams per liter 40 Phytic acid in aqueous solution (70% phytic acid by weight), ml. per liter 20 Zinc oxide, grams per liter 2 The pH of the above solution was adjusted to 12 by adding sodium hydroxide thereto. The electrolyte solution was then placed in a tank having a stainless steel anode and a steel strip inch wide and 7 /2 inches long and 0.020 inch thick was connected as the cathode. A potential of 33 volts was applied to produce a current density of 12.5 amperes per square foot for minutes. The plating was carried out at a temperature of 80 F. There resulted an improved copper coating on the steel strip.

In certain cases it is desirable to electroplate an alloy of copper and zinc on the base metal and to impart to 4 the coating a typical brass color. Such a coating canreadily be obtained using the present invention and the following is an example of the electrolyte and method for forming such a coating.

EXAMPLE 3 i amounts indicated.

Copper tartrate, grams per liter 40 Aqueous solution of phytic acid (70% phytic acid by weight), ml. per liter 20 Zinc oxide, grams per liter 4 Sufficient sodium hydroxide solution was added to raise the pH to 12.4. The electrolyte solution thus formed was placed in a tank having an anode of copper and a steel strip of the dimensions set forth in Example 2 as the cathode. The temperature of the solution was adjusted to F. and a potential was impressed thereon to provide a current density of 50 ampercs per square foot. The steel strip was coated for 5 minutes after which it was removed and bolted. The resultant coating was shiny and bronze in color. The coating also was adherent and generally of good quality.

More complicated copper base alloys can be successfully coated on base metals using the present invention. The following is an example of the formation of a bronze coating on a steel strip.

4 EXAMPLE 4 A coating solution was formed by adding the following ingredients to water to provide the concentrations indicated.

Copper sulfate pentahydrate, grams per liter 40 Tin sulfate, grams per liter 2 Zinc oxide, gram per liter l Aqueous solution of phytic acid (70% by weight), ml.

per liter 30 Sutficient ammonium hydroxide solution was added to adjust the pH to about 9.3. A stainless steel anode was provided for the electrolyte and a steel strip provided as the cathode. A plating potential was impressed thereon to provide a plating current having a density of ampcres per square foot. The plating was continued at room temperature for 5 minutes. The resultant coating was adherent and had a distinctive bronze color.

The following are examples of the electroplating of nickel on base metals utilizing the presentinvention.

EXAMPLE 5 The following ingredients were mixed in an aqueous solution in the concentrations designated.

Nickel chloride hexahydrate, grams per liter 81 Aqueous solution of phytic acid (70% by weight), ml.

per liter 27 EXAMPLE 6 The following ingredients were mixed in aqueous solution in the concentrations indicated.

Nickel chloride hexahydrate, grams per liter 81 Aqueous solution of'phytic acid (70% by weight), ml.

per liter 55 The pH of the above electrolyte was 0.7. A copper strip was arranged as the cathode and a stainless steel strip as the anode in the electrolyte solution. A plating potential sufficient to produce a current density at the copper strip of 160 amperes per square foot was impressed. The plating current was applied for 5 minutes at a temperature of- 75 F. The resultant coating had a good nickel color and was tightly adherent to the copper strip.

The method of the present invention can also be utilized to form coatings of cobalt. The following is an example of the formation of an electrodeposited coating of cobalt on a copper base utilizing the present invention.

EXAMPLE 7 The following ingredients were mixed in the propertions indicated in water.

Cobalt sulfate heptahydrate, grams per liter 53 Aqueous solution of phytic acid (70% by weight), ml.

per liter 26 EXAMPLE 8 The following ingredients were mixed in an aqueous solution in the proportions indicated.

Tin chloride (SnCl -2H O), grams per liter 46 Sodium phytate solution (35% by weight), ml. per

liter 32 Sodium hydroxide, grams per liter 70 The pH of the above electrolyte solution was 12.1. A

stainless steel anode was provided and a copper strip served as the cathode to be coated. A plating potential of 1.25 volts was impressed thereon to produce a current density of 43 amperes per square foot on the copper strip. Electroplating was carried out for 30 seconds at 75 F. There resulted a uniform and tightly adherent coating of tin on the copper strip.

The following is an example of the use of the present invention to provide an electrodeposited coating of cadmium on a base metal.

EXAMPLE 9 An electrolyte solution was prepared by mixing the following ingredients in the proportions indicated.

Cadmium chloride (CdCl /2H O), grams per liter 40.6 Aqueous solution of phytic acid (70% by weight),

ml. per liter 15 The pH of the above electrolyte solution was 1.5. A copper strip was provided as the cathode and a stainless steel strip as the anode. A plating potential of 5.1 volts was impressed thereon to provide a current density of 80 amperes per square foot at the copper strip. The plating operation was carried out for 15 minutes at a temperature of 75 F. There resulted a typical cadmium coating which was adherent to the copper base metal.

It has been found that a blue-black coating of tungsten can also be provided on base metals utilizing the present invention.

EXAMPLE 10 The following ingredients were mixed in water in the amounts indicated.

Tungstic acid, grams per liter 27 Aqueous solution of phytic acid (70% by weight),

ml. per liter 25 Suflieient ammonium hydroxide solution was added toprovide a pH of 11. A stainless steel anode was provided and a copper strip was utilized as the cathode. A plating potential of 2.75 volts was impressed to provide a current density of 43 amperes per square foot at the surface of the copper strip. The plating current was applied for 10 minutes at a temperature of 75 F. There resulted a tightly adherent blue-black coating of tungsten on the copper strip.

The following is an example of the plating of manganese on a base metal utilizing the present invention.

EXAMPLE 1 1 An electrolyte solution was provided by adding the following ingredients to water in the proportions indicated.

Manganese sulfate monohydrate, grams per liter Aqueous solution of phytic acid (70% by weight),

ml. per liter 5O Suflicient sodium hydroxide was added to adjust the pH to 5.0. A stainless steel anode was provided and a copper strip was utilized as the cathode. A plating potential was impressed to provide a plating current of amperes per square foot. The plating was carried out at room temperature for a period of 15 minutes. A good coating of manganese was formed on the copper strip.

Lead coatings can also be formed on base metals utilizing this invention.

EXAMPLE 12 An aqueous electrolyte was provided by adding the following ingredients to water in the amounts indicated.-

Lead nitrate, grams per liter 32 Aqueous solution of sodium phytate (35% by weight), ml. per liter 30 Sodium hydroxide, grams per liter 108.

The pH of the above electrolyte solution was 11.9. A stainless steel anode and a copper strip cathode were provided in the electrolyte solution. A plating potential of 0.7 volt was employed to provide a plating current density of 43 amperes per square foot at the surface of the copper strip. The plating operation was carried out for 30 seconds at room temperature to provide a lead coating on the copper strip.

Coatings of zinc can be provided on base metals, the zinc being the only metal present in the coating as contrasted with Examples 2 and 3 above wherein the zinc was present as one of the ingredients in an alloy coating.

EXAMPLE 13 The following ingredients were mixed in water in the amounts indicated.

Sufficient ammonium hydroxide was addedto provide a pH of 9.3. A stainless steel anode and a steel strip as a cathode were provided in the electrolyte solution. A plating voltage of 4.5 volts was impressed thereon to provide a current density of 45 amperes per square foot on the surface of the steel strip. The plating operation was carried out for 30 minutes at a temperature of 83 F. There resulted a good adherent coating of zinc on the steel strip.

From Examples 1 through 13 above it is seen that a wide variety of metal coatings and metal alloy coatings can be provided on base metals utilizing the present invention. More specifically the metals of group 113 can be used to form coatings, copper being an example of this group of metals. Zinc and cadmium from the metals of group IIB are exemplified above as suitable materials to provide coatings using the present invention. Tin and lead from group IVA demonstrate that this group of metals can also be used to provide coatings by means of the present invention. Tungsten from group VIB and manganese from group VIIB are also exemplified above. Cobalt and nickel from groupVIII illustrate the formation of coatings of that group of metals utilizing the present invention. It is seen therefore that a wide variety of metals can be successfully electroplated on base metals by means of this invention.

It has further been found that the current density has a marked effect upon the character of the coating obtained as well as the weight and thickness thereof. The following table illustrates the effect of a change in current density on the coating. Each of Examples 14 through 23 utilizes the same electrolyte and the same plating temperature and plating time. More specifically the following electrolyte was provided by mixing the ingredients indicated in water in the amounts indicated.

Copper sulfate pentahydrate, grams per liter 40 Aqueous solution of phytic acid (70% by weight),

ml. per liter 30 The pH of the solution Was adjusted to 9.3 by adding ammonium hydroxide. A stainless steel anode and a steel strip as cathode were utilized. The plating temperature was 83 F.:l F. and the plating time was 30 minutes. The effect of changing the plating current and the plating voltage whereby to change the current density at the cathode is illustrated and the effect on the thickness of the copper coating obtained is illustrated.

Table 1 Current Copper Sample Plating Plating Density, on Steel Example .Area, Current, Volta e, Amps! Strip,

Ft. Amps. Volts Ft. OZJFU Surface Surface The adhesion of the copper coating to the steel strip was superior at current densities above 90 amperes per square foot.

It was also found that the plating current density had an eifect upon the amount of zinc coating formed for a given unit of time. The electrolyte solution and method of Example 13 above was repeated utilizing both smaller current densities and larger current densities. The eifect of changing the current density on the weight of zinc coating deposited per square foot of surface area is set forth in Table II.

Table 11 Current Zinc Sample Plating Plating Density, Coating, Example Area, Ft. Current, Voltage, Amps] Oz./Ft.

of Surface Amps. Volts Ft. Surface Surface There is shown in Table III below the eitect of varying the current density on the amount of tin plated on a steel strip utilizing the present invention. Each of these examples utilized an electrolyte formed by adding the following ingredients to water.

Stannous sulfate, grams per liter 2 Aqueous solution of phytic acid (70% by weight),

ml. per liter 30 'Suflicient ammonium hydroxide Was added to provide a pH of 9.3. A steel strip was plated at a temperature of 83 F.- -1 F. for 30 minutes. The following table summarizes the effect of changing the current density on the weight of tin coating formed on the steel strip.

Table II I Sample Current 'lin Area, Plating Plating Density, Coating, Example Ft. of Current, Voltage, Amps] OzJFt. Surface Amps. Volts It. Surface Surface There is shown in Table IV the effect on composition of a bronze alloy coating brought about by changing the current density during electroplating. In each of examples 39 through 47 of Table IV, an electrolyte solution including the following ingredients in the amounts indicated was utilized.

Copper sulfate pentahydrate, gram per liter Stannous sulfate, grams per liter 2.0 Zine oxide, gram per liter 1.0 Aqeous solution of phytic acid (70% by weight),

ml. 'per liter 30 The pH was adjusted to 9.3 by adding ammonium hydroxide. A steel strip was plated at a temperature of 83 F.i1 F. for 30 minutes. The effect on the alloy coating composition by varying the current density is illustrated in Table IV.

Table IV Current Coating Analysis, OzJFt. Surface Sample Plating Plating Density Example Area, Ft. Current, Voltage, Amps/ Surface Amps. Volts Ft. Cuv Zn Sn Total Surface Metal It will be seen from Table IV above that there was no coating deposited when operating at the lower current densities, as represented in Examples 39 and 40. At slightly higher current densities only copper was plated out on the base metal as is exemplified by Examples 41, 42 and 43. At the current density of approximately 68 amps. per square foot, copper and zinc were both present in the plated coating, see Example 44. At higher current densities, i.e. above about 90 amps. per square foot, all three of the metals present in the electrolyte solution were deposited in the coating. The coatings formed in Examples 45, 46 and 47 all had a typical bronze color with excellent adhesion.

From the several examples given above it will be seen that various concentrations of the phytate complexing anion may be used, and furthermore that the molar ratio between the metal cations in the solution and the complexing phytate anions in the solution may vary substantially. The ratio between the metal cations present and the complexing anions present may be as low as about 1:5, as in Examples 31 through 38 above. Conversely, the ratio between the metal coating cations and the complexing anions may be as high as :1, as in Example 8 above. It is desirable that a substantial portion of the cations in the solution be complexed by the phytate ions present. In general superior results are obtained if the amount of phytate ion present is sufiicient to form a complex with substantially all of the metallic coating ions in the electrolyte solution.

A wide range of pH may be utilized in the present method. The pH may be as low as 0.7, as illustrated in Example 6 above, or even lower, and may be as high as 12.4, as in Example 3 above. In general the electroplating method may be successfully operated Within the pH range of 0.5 to about 13, the pH being chosen to insure that the metal cations needed to form the coating are soluble in the electrolyte solution and that the complexing agent, such as the phytate ion, is also soluble.

One important advantage of the present invention is the fact that the electroplating operation can be carried out at approximately room temperatures. However, the electroplating method has been successfully operated at lower temperatures and also at higher temperatures.

In carrying out the examples set forth above, the phytate ion used has been added in a relatively pure state. It has been found, however, that it is not necessary to use substantially pure phytic acid or a salt thereof, and in fact waste solutions or concentrated waste solutions resulting from steeping of grains called steep liquors are sufiiciently rich in phytate acid to be used satisfactorily. These liquors contain about 10 to 13 percent phytic acid by weight. The other impurities found therein do not interfere with the electroplating.

Another advantage of the present electroplating method and electrolyte solution is that the coating formed thereby also has a protective coating therein comprising an ion of the complexing agent such as the phytate ion. This results from the fact that the coating surface is in contact with a solution containing phytate ions which react with thecoating surface to provide a protective coating, as is more fully set forth in my co-pending application, Serial No. 724,794, filed March 31, 1958, for Protective Coatings on Metals.

A wide range of current densities has been illustrated in the examples given above. It has been found that the present invention is useful when the current densities utilized are in the range of about 10 amperes per square foot to 10,000 amperes per square foot.

The present application is a continuation-in-part of my previously filed patent application, Serial No. 641,248, filed February 20, 1957, for Copper Plating and Electrolyte Therefor, now abandoned.

Although certain preferred examples of the invention have been given for the purpose of illustration, it should be understood that various changes and modifications can be made therein without departing from the spirit and scope of the invention. Accordingly, it-is intended to cover all modifications and equivalents of the invention' which come within the scope of the appended claims.

I claim:

1. An electrolytic bath for forming coatings of metals on a base metal comprising a solution containing cations of a coating metal selected from the group consisting of copper, zinc, tin, nickel, cobalt, cadmium, tungsten, manganese and lead and alloys predominately of said metals, and complexing anions of a phosphoric acid ester of a cyclohexanol, said complexing anions being present in an amount sufiicient to form a complex with a substantial amount of the coating metal cations present in the solution.

2. An electrolytic bath for forming coatings of metals on a base metal comprising a solution containing cations. of a coating metal selected from the group consisting of copper, zinc, tin, nickel, cobalt, cadmium, tungsten, manganese and lead and alloys predominately of said metals, and conrplexing anions of a phosphoric acid ester of inositol, said complexing anions being present in an amount sufiicient to form a complex with a substantial amount of the coating metal cations present in the solu- Hon.

3. An electrolytic bath for forming coatings of metals on a base metal comprising a solution containing cations of a coating metal selected from the group consisting of copper, zinc, tin, nickel, cobalt, cadmium, tungsten, manganese and lead and alloys predominately of said metals, and soluble phytate ions, said phytate ions being present in an amount suflicient to form a complex with a substantial amount of the coating metal cations present in the solution.

4. An electrolytic bath for forming layers substantially of copper metal comprising a solution containing copper ions and phytate ions, said phytate ions being present in an amount sufficient to form a complex with substantially all of the copper ions present in solution. I

5. An electrolytic bath for forming layers substantially of copper metal comprising a solution of phytin-phosphate and copper tartrate in water, said phytin-phosphate being present in an amount sufficientto form a complex with substantially all of the copper ions present in solution.

6. An electrolytic bath for forming layers substantially of copper metal comprising a solution of phytin-phosphate and copper sulphate in water, said phytin-phosphate being present in an amount sutlicient to form a complex with substantially all of the copper ions present in solution.

7. An electrolytic bath for forming layers substantially. of copper metal comprising a solution of phytin-phosphate and copper carbonate in water, said phytin-phosphate being present in an amount suflicient to form a complex with substantially all of the copper ions present in solution.

8. An electrolytic bath for forming layers substantially of copper metal comprising a solution in water of sodium phytate and copper tartrate in the proportion of from 8 to 14 ounces of sodium phytate and copper tartrate for each gallon of water, the phytate ions in solution being present in an amount sufiicient to form a complex with substantially all of the copper ion present in solution.

9. An electrolytic bath for forming coatings of nickel on a base metal comprising a solution containing nickel ions and phytate ions, said phytate ions being present in an amount suflicient to form a complex with a substantial amount of the nickel cations present in the solution.

10. An electrolytic bath for forming coatings of cobalt on a base metal comprising a solution containing cobalt ions and phytate ions, said phytate ions being present in an amount sutficient to form a complex with a substantial amount 'sufiicient to form a complex. with a substantial amount of the tin ions present in the solution.

12. An electrolytic bath for forming coatings of cadmium on a base metal comprising a solution containing cadmium ions and phytate ions, said phytate ions being present in an amount sufficient to form a complex with a substantial amount of the cadmium ions present in the solution.

13. An electrolytic bath for forming coatings of tungsten on a base metal comprising a solution containing tungsten ions and phytate ions, said phytate ions being present in an amount sufiicient to form a complex with a substantial amount of the tungsten ions present in the solution.

14. An electrolytic bath for forming coatings of manganese on a base metal comprising a solution containing manganese ions and phytate ions, said phytate ions being present in an amount sufiicient to form a complex with a substantial amount of the manganese ions present in, the solution.

15. An electrolytic bath for forming coatings of lead on a base metal comprising a solution containing lead ions and phytate ions, said phytate ions being present in an amount suflicient to form a complex with a substantial amount of the lead ions present in the solution.

16. An electrolytic bath for forming coatings of zinc on a base metal'cornprising a solution containing zinc ions and phytate ions, said phytate ions being present in an amount sufiicient to form a complex with a substantial amount of the zinc ions present in the solution.

17. An electrolytic bath for forrm'ng a copper colored coating on a base metal comprising a solution containing copper ions and zinc ions and phytate ions, the molar ratio of the copper ions to the Zinc ions being at least :1, said phytate ions being present in an amount sufiicient to form a complex With substantially all of the copper ions and the zinc ions present in the solution.

18. An electrolytic bath for forming brass colored coatings on a base metal comprising a solution containing copper ions and zinc ions and phytate ions, the molar ratio of the copper ions to the zinc ions being less than about 5:1, said phytate ions being present in an amount sufficient to form a complex with substantially all of the zinc ions and the copper ions in the solution.

19. An electrolytic bath for forming bronze coatings one base metal comprising a solution containing copper ions and tin ions and zinc ions and phytate ions, said phytate ions being present in an amount sufficient to form a complex with a substantial amount of the copper ions and the tin ions and the zinc ions present in the solution.

'20. The method of electroplating a metal coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing cations of a coating metal selected from the group consisiting of copper, Zinc, tin, nickel, cobalt, cadmium, tungsten, manganese and lead and alloys predominately of said metals, and anions of a phosphoric acid ester of a cyclohexanol, said anions being present in an amount sutiicient to form a complex with a substantial amount of the coating metal cations present in the solution.

21. The method of electroplating a metal coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing cations of a coating metal selected from the group consisting of copper, zinc, tin, nickel, cobalt, cadmium, tungsten, manganese and lead and alloys predominately of said metals, and anions of a phosphoric acid ester of inositol, said anions being present in an amount suflicient to form a complex with a substantial amount of the coating metal cations present in the solution.

22. The method of electroplating a metal coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing cations of a coating metal selected from the group con- 12 sisting of copper, zinc, tin, nickel, cobalt, cadmium, tungsten, manganese and lead and, alloys predominately of said metals, and phytate anions, said phytate ions being present in an amount sufiicient to form a complex with a substantial amount of the coating metal cations present in the solution.

23. The method of effecting the electrolytic deposition of layers substantially of copper on metal which comprises the steps of immersing the metal as a cathode in an electrolytic bath containing a copper anode and a solution of phytin-phosphate and water, the phytin-phospnate being present in an amount suflicient to form a complex with substantially all of the copper ion present in solution.

24. The method of effecting the electrolytic deposition of layers substantially of copper on metal which comprises the steps of immersing the metal as a cathode in an electrolytic bath containing a copper anode and a solution of phytin-phosphate, copper salt and water, the phytin-phosphate being present in an amount sufiicient to form a complex with substantially all of the copper ion present in solution.

25. The method of effecting the electrolytic deposition of layers substantially of copper on metal which comprises the steps of immersing the metal as a cathode in an electrolytic bath containing a copper anode and a solution of phytin-phosphate, copper tartrate and Water, the phytin-phosphate being present in an amount sufficient to form a complex with substantially all of the copper ion present in solution.

26. The method of effecting the electrolytic deposition of layers substantially of copper on metal which comprises the steps of immersing the metal as a cathode in an electrolytic bath containing a copper anode and a solution of sodium phytate, copper tartrate and Water, combined in the proportions of from 8 to 14 ounces of sodium phytate and copper tartrate for each gallon of water, the phytate ion in solution being present in an amount sufiicient to form a complex with substantially all of the copper ion present in solution.

27. The method of effecting the electrolytic deposition of layers substantially of copper on metal which comprises the steps of immersing the metal as a cathode in an electrolytic bath containing a copper anode and a solution of phytin-phosphate, copper salt and water, said phytin-phosphate being present in an amount sufficient to form a complex with substantially all of the copper ion present in solution and maintaining the pH of the solution substantially at 9.5.

28. The method of electroplating a nickel coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing nickel ions and phytate ions, said phytate ions being present in an amount sufficient to form a complex with a substantial amount of the nickel ions present in the solution.

29. The method of electroplating a cobalt coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing cobalt ions and phytate ions, said phytate ions being present in an amount sufiicient to form a complex with a substantial amount of the cobalt ions present in the solution.

30. The method of electroplating of tin coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing tin ions and phytate ions, said phytate ions being present in an amount sufficient to form a complex with a substantial amount of the tin ions present in the solution.

31. The method of electroplating a cadmium coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing cadmium ions and phytate ions, said phytate ions being present in an amount suflicient to form a complex with a substantial amount of the cadmium ions present in the solution.

32. The method of electroplating a tungsten coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing tungsten ions and phytate ions, said phytate ions being present in an amount suflicient to form a complex with a substantial amount of the tungsten ions present in the solution.

33. The method of electroplating a manganese coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing manganese ions and phytate ions, said phytate ions being present in an amount sufficient to form a complex with a substantial amount of the manganese ions present in the solution.

34. The method of electroplating a lead coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing lead ions and phytate ions, said phytate ions being present in an amount sufiicient to form a complex with a substantial amount of the lead ions present in the solution.

35. The method of electroplating a zinc coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing zinc ions and phytate ions, said phytate ions being present in an amount sufficient to form a complex with a substantial amount of the zinc ions present in the solution.-

36. The method of electroplating a copper colored coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing copper ions and zinc ions and phytate ions, the molar ratio of the copper ions to the zinc ions being at least about :1, said phytate ions being present in an amount sufficient to form a complex with substantially all of the copper ions and the zinc ions present in the solution.

37. The method of electroplating a brass colored coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing copper ions and zinc ions and phytate ions, the molor ratio of the copper ions to the zinc ions being less than about 5 1, said phytate ions being present in an amount sufiicient to form a complex with substantially all of the copper ions and the zinc ions present in the solution.

38. The method of electroplating a bronze colored coating on a base metal which comprises the steps of immersing the base metal as a cathode in an electrolytic bath containing copper ions and zinc ions and tin ions and phytate ions, said phytate ions being present in an amount suflicient to form a complex with substantially all of the copper ions and the zinc ions and the tin ions present in the solution.

39. The method of electroplating a bronze colored coating on a base metal which comprises the steps of immersing the base metal as a cathode and providing an anode in an electrolytic bath containing copper ions and zinc ions and tin ions and phytate ions, said phytate ions being present in an amount sufiicient to form a complex with substantially all of the copper ions and the zinc ions and the tin ions present in the solution, and passing a plating current between said cathode and said anode to provide a current density of at least 90 amperes per square foot on the surface of the base metal cathode.

40. A composition for electrolytic baths for forming coatings of metals on a base metal comprising a first compound soluble in the electrolytic bath and containing a soluble cation of a coating metal selected from the group consisting of copper, zinc, tin, nickel, cobalt, cadmium, tungsten, manganese, lead and alloys predominately of said metals, and a second compound soluble in the electrolytic bath and selected from the class consisting of a phosphoric acid ester of a cyclohexanol and salts thereof, said second compound being present in an amount sufiicient to form a complex with 14 a substantial amount of the coating metal cations present in the electrolytic bath.

41. A composition for electrolytic baths for forming coatings of metals on a base metal comprising a first compound soluble in the electrolytic bath and containing a soluble cation of a coating metal selected from the group consisting of copper, zinc, tin, nickel, cobalt, cadmium, tungsten, manganese, lead and alloys predominately of said metals, and a second compound soluble in the electrolytic bath and selected from the class consisting of a phosphoric acid ester of inositol and salts thereof, said second compound being present in an amount suflicient to form a complex with a substantial amount of the coating metal cations present in the electrolytic bath.

42. A composition for electrolytic baths for forming coatings of metals on a base metal comprising a first compound soluble in the electrolytic bath and containing a soluble cation of a coating metal selected from the group consisting of copper, zinc, tin, nickel, cobalt, cadmium, tungsten, manganese, lead and alloys predominately of said metals, and a second compound soluble in the electrolytic bath and selected from the class consisting of phytic acid and salts thereof, said second compound being present in an amount suflicient to form a complex with a substantial amount of the coating metal cations present in the electrolytic bath.

43. A composition for electrolytic baths for forming copper coatings on a base metal comprising a compound of copper soluble in the electrolytic bath, and a second compound soluble in the electrolytic bath and selected from the class consisting of phytic acid and salts thereof, said second compound being present in an amount sufficient to form a complex with a substantial amount of the copper ions present in the electrolytic bath.

44. A composition for electrolytic baths for forming a copper colored coating on a base metal comprising a copper compound soluble in the electrolytic bath, a Zinc compound soluble in the electrolytic bath, and a phytate compound selected from the class consisting of phytic acid and salts thereof, the molar ratio of said copper compound to said zinc compound being at least 5:1, said phytate compound being present in an amount suflicient to form a complex with a substantial amount of the copper ions and the zinc ions present in the electrolytic bath.

45. A composition for electrolytic baths for forming a copper colored coating on a base metal comprising a copper compound soluble in the electrolytic bath, a zinc compound soluble in the electrolytic bath, and a phytate compound selected from the class consisting of phytic acid and salts thereof, the molar ratio of said copper compound to said zinc compound being less than about 5 :1, said phytate compound being present in an amount sufiicient to form a complex with a substantial amount of the copper ions and the zinc ions present in the electrolytic bath.

46. A composition for electrolytic baths for forming a bronze colored coating on a base metal comprising a copper compound soluble in the electrolytic bath, a zinc compound soluble in the electrolytic bath, a tin compound soluble in the electrolytic bath, and a phytate compound selected from the class consisting of phytic acid and salts thereof, said phytate compound being present in an amount sufiicient to form a complex with a substantial amount of the copper ions and the zinc ions and the tin ions present in the electrolytic bath.

47. A composition for electrolytic baths for forming zinc coatings on a base metal comprising a compound of zinc soluble in the electrolytic bath, and a second compound soluble in the electrolytic bath and selected from the class consisting of phytic acid and salts thereof, said second compound being present in an amount suflicient to form a complex with a substantial amount of the zinc ions present in the electrolytic bath.

48'. A composition for electrolytic baths for forming tin coatings on a base metal comprising a compound of tin soluble in the electrolytic bath, and a second compound soluble in the electrolytic bath and selected from the class consisting of phytic acid and salts thereof, said second compound being present in an amount sufficient to form a complex with a substantial amount of the tin ions present in the electrolytic bath.

49. A composition for electrolytic baths for forming nickel coatings on a base metal comprising a compound of nickel soluble in the electrolytic bath, and a second compound soluble in the electrolytic bath and selected from the class consisting of phytic acid and salts thereof, said second compound being present in an amount sulficient to form a complex with a substantial amount of the nickel ions present in the electrolytic bath.

50. A composition for electrolytic baths for forming cobalt coatings on a base metal comprising a compound of cobalt soluble in the electrolytic bath, and a second compound soluble in the electrolytic bath and selected from the class consisting of phytic acid and salts thereof, said second compound being present in an amount sufficient to form a complex with a substantial amount of the cobalt ions present in the electrolytic bath.

51. A composition for electrolytic baths for forming cadmium coatings on a base metal comprising a compound of cadmium soluble in the electrolytic bath, and a second compound soluble in the electrolytic bath and selected from the class consisting of phytic acid and salts thereof, said second compound being present in an amount sufficient to form a complex with a substantial amount of the cadmium ions present in the electrolytic bath.

52. A composition for electrolytic baths for forming tungsten coatings on a base metal comprising a compound of' tungsten soluble in the electrolytic bath, and a second compound soluble in the electrolytic bath and selected from the class consisting of phytic acid and salts thereof, said second compound being present in an amount suflicient to form a complex with a substantial amount of the tungsten ions present in the electrolytic bath.

53. A composition for electrolytic baths for forming manganese coatings on a base metal comprising a compound of manganese soluble in the electrolytic bath, and a second compound soluble in the electrolytic bath and selected from the class consisting of phytic acid and salts thereof, said second compound being present in an amount sufiicient to form a complex with a substantial amount of manganese ions present in the electrolytic bath.

54. A composition for electrolytic baths for forming lead coatings on a basernetal comprising a compound of lead soluble in the electrolytic bath, and a second com pound soluble in the electrolytic bath and selected from the class consisting of phytic acid and salts thereof, said second compound being present in an amount sufficient to form a complex with a substantial amount of lead ions present in the electrolytic bath.

References Cited in the file of this patent UNITED STATES PATENTS Breining et al. Feb. 11, 1958 Prick et al. Aug. 5, 1958 

1. AN ELECTROLYTIC BATH FOR FORMING COATINGS OF METALS ON A BASE METAL COMPRISING A SOLUTIN CONTAINING CATIONS OF A COATING METAL SELECTED FROM THE GROUP CONSISTING OF COPPER, ZINC, TIN, NICKEL, COBALT, CADMIUM, TUNGSTEN, MANGANESE AND LEAD AND ALLOYS PREDOMINATELY OF SAID METALS, AND COMPLEXING ANIONS OF A PHOSPHORIC ACID ESTER OF A CYCLOHEXANOL, SAID COMPLEXING ANIONS BEING PRESENT IN AN AMOUNT SUFFICIENT TO FORM A COMPLEX WITH A SUBSTANTIAL AMOUNT OF THE COATING METAL CATIONS PRESENT IN THE SOLUTION. 